Falls in the elderly cause injuries, as well as psychosocial problems, which result in an enormous burden on the individuals who fall, the caregivers and the health care system. The proposed research is intended to provide information that will further understanding of the causes of falls and aid in the development of new interventions for fall prevention. Recent studies by the applicants have documented the importance of corrective stepping in the maintenance of upright posture, and have also shown that deterioration in the control of lateral postural sway is predictive of falling risk in the elderly. In spite of the possible importance of these responses, both stepping and lateral balance control are poorly documented. Available information would suggest, however, that each of these responses require accurate pressure information from the plantar surface of the feet. It is therefore hypothesized that an increased risk of falling in the elderly may result from decreased sensitivity of plantar pressure receptors, causing problems in the execution of stepping or lateral balance recovery responses. This study will attempt to determine whether facilitating sensation from the soles of the feet in healthy elderly subjects will lead to improved control of lateral balance and compensatory stepping. Postural responses will be measured in various balance tasks with and without the benefit of facilitated cutaneous discharge. Subjects will stand on indentor plates, previously shown to have an influence on the degree of postural sway, in order to facilitate the cutaneous drive. The postural tasks will involve maintaining equilibrium during quiet standing and in response to unpredictable multi-directional perturbations. Responses to both sudden transient and continuous pseudorandom platform motions will be studied, since the duration and nature of the stimulus may strongly influence the demand for sensory information. Both "feet-in-place" and stepping responses will be studied, and postural responses will be characterized in terms of ground reaction forces, as well as muscle activation and patterns of body motion. It is anticipated by the applicants that the study will generate new knowledge about the contributions of plantar pressure sensation to postural control and could lead to novel interventions, such as special footwear or floor surfaces, that could supplement this sensory source to improve functional balance and prevent falls in the elderly.